Mill--How to Choose

[ACHiPo]

As the title says, I'm trying to figure out which mill to get for my first mill. I don't have room for a Bridgeport, so I've pretty much settled on a decent sized bench-top mill.

The PM833T seems to have a lot of good features, and at just under 1k lbs., seems solid for a smaller mill, while at the same time small enough to mount to a mobile base, ideally with a Vidmar or equivalent underneath.

What other considerations am I missing?

 

[Poppey]

I'm very happy with my X3 mill. I have replaced the motor with a 2 hk treadmill motor and a new drive. I took it apart and cleaned it as per ARC Eurotrade instruction.


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[mikey]

As the title says, I'm trying to figure out which mill to get for my first mill. I don't have room for a Bridgeport, so I've pretty much settled on a decent sized bench-top mill.

The PM833T seems to have a lot of good features, and at just under 1k lbs., seems solid for a smaller mill, while at the same time small enough to mount to a mobile base, ideally with a Vidmar or equivalent underneath.

What other considerations am I missing?

Are you asking us to validate your choice? If so, the PM833T is a really nicely spec'd benchtop mill that looks to be a great mill for a hobby shop. It lacks a DRO, hardened ways and maybe a higher top speed but it has everything else. As long as you understand this is a light-duty mill and use it accordingly it will be a great addition to you shop, or my shop, or most hobby guy's shops.

There are better mills out there, knee mills for example. Your 833 has to move the head to adjust height in Z so rigidity is not as good as a knee, nor is it as accurate. Most knee mills have a more robust spindle, typically in a cartridge with at least 4 bearings supporting the spindle. The 833 probably has two bearings at the top and bottom; they may be ABEC 5 equivalents but they're still only two bearings so you won't be taking monster cuts with that machine. Mass is king with milling machines and you really see this when you bore a big hole with a boring head. Since we don't bore that often, this isn't a big deal but its a real thing. Space-wise, a Bridgeport sized mill doesn't take a huge amount more space than a benchtop - I would guess under a foot or so.

If you want a bench top mill, that 833 has some really nice features and specs. I would love to own one, but if I buy another mill it will be a knee mill. I've used both and for rigidity and mass, you cannot beat a knee mill.

 

[ACHiPo]

Are you asking us to validate your choice? If so, the PM833T is a really nicely spec'd benchtop mill that looks to be a great mill for a hobby shop. It lacks a DRO, hardened ways and maybe a higher top speed but it has everything else. As long as you understand this is a light-duty mill and use it accordingly it will be a great addition to you shop, or my shop, or most hobby guy's shops.

There are better mills out there, knee mills for example. Your 833 has to move the head to adjust height in Z so rigidity is not as good as a knee, nor is it as accurate. Most knee mills have a more robust spindle, typically in a cartridge with at least 4 bearings supporting the spindle. The 833 probably has two bearings at the top and bottom; they may be ABEC 5 equivalents but they're still only two bearings so you won't be taking monster cuts with that machine. Mass is king with milling machines and you really see this when you bore a big hole with a boring head. Since we don't bore that often, this isn't a big deal but its a real thing. Space-wise, a Bridgeport sized mill doesn't take a huge amount more space than a benchtop - I would guess under a foot or so.

If you want a bench top mill, that 833 has some really nice features and specs. I would love to own one, but if I buy another mill it will be a knee mill. I've used both and for rigidity and mass, you cannot beat a knee mill.

Mike,

Thanks. Your explanation helps a lot. I actually sent Matt a question about whether the ways are hardened and haven't gotten an answer back--I'm guessing since it doesn't say they are, they aren't?

I'm not really looking for validation, but am trying to understand what the limitations will be with a benchtop machine (even one as big and powerful as the 833). At this point, I don't know what I don't know, but I don't want to commit to a BP-sized knee mill (it's really more the weight than size as you say--although I'm re-thinking that).

Evan

 

[mikey]

Please don't misunderstand me, Evan. That 833 is an awesome machine and it will do everything you want unless you're making big stuff most of the time. I looked at that machine when Matt first listed it on ebay and it is really well spec'd. It has all the right stuff and the things I pointed out are not deal breakers at all. This is your first mill and for a first mill, it would be hard to do better, especially if you have a weight or size restriction. Talk to Matt and he can advise you better.

In broad strokes, you can get a real knee mill or a benchtop mill. Both do the same thing, albeit in different ways like moving the head vs the knee, etc. The knee and mass of a big mill are major advantages but for smaller hobby use, a benchtop is suitable for the vast majority of us. This need not be your last mill; it is only the first. You will know what works for you in the first year or two and you can decide if it is the right machine for you.

So, bottom line (in my opinion): The 833 is a very, very nice machine. It is built to a higher standard than most benchtop machines out there and is priced decently. If you want a benchtop and do not need one of Matt's larger benchtops, this one should work very well for you. No matter which mill you buy, there will be pros and cons and you either upgrade or learn to live with them. I suspect the 833 will be very easy to live with.

 

[ACHiPo]

Mike,
Great advice. I'm definitely noodling on it (and continuing to look for decent, affordable used iron).

Part of what I'm struggling with is getting used to the idea of moving around very heavy lumps by myself. So far I've avoided having anything other than my woodworking bench being immobile. Even if I put wheels on a knee mill, it will be pretty tough to move around (lots of inertia!)

Oh, and I've already decided whichever way I end up going, my mill will have DRO, which Matt will add for a few hundred (to a thousand) depending on number of axes and type.

Evan

 

[talvare]

Evan,

Which type of mill you choose should be determined by the type of work you intend to do, both now and in the future and of course, the space you have available. The bench top mills work perfectly well for a lot of guys and it may well do everything you ever intend to do. But if you think you'll be doing heavier or larger milling projects at some time, then you may be better served with a knee mill. In the price range that you're considering, there are some pretty nice used knee mills on the market. Also, the bench top mill may give up a few features that a typical BP style knee mill has such as the ability to nod the head, extend the ram fore and aft, rotate the turret right and left, raise and lower the table, etc. Some of these features don't get used often, but I have found that sooner or later I've needed all of them.
Just my two cents.

Ted

 

[mikey]

Mike,
Great advice. I'm definitely noodling on it (and continuing to look for decent, affordable used iron).

Part of what I'm struggling with is getting used to the idea of moving around very heavy lumps by myself. So far I've avoided having anything other than my woodworking bench being immobile. Even if I put wheels on a knee mill, it will be pretty tough to move around (lots of inertia!)

Oh, and I've already decided whichever way I end up going, my mill will have DRO, which Matt will add for a few hundred (to a thousand) depending on number of axes and type.

Evan

Having a top-heavy machine on wheels is always a concern but if your shop floor is smooth and flat then it isn't that big a deal. My mill is only 800# and my lathe is about 600# and both are on Carrymaster casters and are a breeze to move easily, by myself. A knee mill would probably benefit from a wider base to perch on but that, too, could be put on casters. Most knee mills are left in one place and you sort of clean and move around them but they can be moved with pipes when needed.

Good luck with this, Evan. Tough decision, especially when the 833 is such a nice package. You might wind up with that mill and maybe have a knee mill sometime in the future.

 

[ACHiPo]

Having a top-heavy machine on wheels is always a concern but if your shop floor is smooth and flat then it isn't that big a deal. My mill is only 800# and my lathe is about 600# and both are on Carrymaster casters and are a breeze to move easily, by myself. A knee mill would probably benefit from a wider base to perch on but that, too, could be put on casters. Most knee mills are left in one place and you sort of clean and move around them but they can be moved with pipes when needed.

Good luck with this, Evan. Tough decision, especially when the 833 is such a nice package. You might wind up with that mill and maybe have a knee mill sometime in the future.

Fortunately my floor is flat and smooth. I have my woodworking band saw on a mobile base (a cheapie from HTC) and it's harder to move and tippier than I'd like--it's probably only about 600 lbs, but has a pretty high center of gravity and the base is less-than-ideal. I put my 12" jointer/planer on a Rockler mobile base with big urethane wheels and it's great to move around. The Carrymaster casters seem to be the way to go for these heavy machines. I still need to get some steel angle iron and plate so I can fabricate the bases.

 

[ACHiPo]

Evan,

Which type of mill you choose should be determined by the type of work you intend to do, both now and in the future and of course, the space you have available. The bench top mills work perfectly well for a lot of guys and it may well do everything you ever intend to do. But if you think you'll be doing heavier or larger milling projects at some time, then you may be better served with a knee mill. In the price range that you're considering, there are some pretty nice used knee mills on the market. Also, the bench top mill may give up a few features that a typical BP style knee mill has such as the ability to nod the head, extend the ram fore and aft, rotate the turret right and left, raise and lower the table, etc. Some of these features don't get used often, but I have found that sooner or later I've needed all of them.
Just my two cents.

Ted

Ted,
I don't see myself doing huge pieces, again because I don't want to deal with anything I can't handle myself. It's more a matter of precision and vibration dampening.

Matt is working on a smallish but full-sized knee mill that will be out later this year at ~1500 lbs.

Evan